This invention relates to the production of arylene sulfide polymers. In one aspect, this invention relates to the production of phenylene sulfide polymers. In another aspect, this invention relates to the production of lighter colored arylene sulfide polymers.
Flexibility in the use of color in fiber and/or mineral reinforced thermoplastic compounds having good mechanical, chemical, thermal and electrical properties is particularly desirable. In applications where such flexibility is desired, a major problem is the preparation of thermoplastic polymers having a consistent degree of whiteness. Failure to attain a consistent degree of whiteness in the polymer results in problems in formulating color compounds that consistently give the desired color.
Arylene sulfide polymers are thermoplastic polymers known in the art, and processes for making these polymers are disclosed in various U.S. patents including, but not limited to, U.S. Pat. Nos. 3,354,129 and 3,919,177. Although these patents represent significant and valuable advances in the art, there is need for a simplified process which can provide arylene sulfide polymers having a consistent degree of whiteness.
A simplified process for achieving consistent whiteness in arylene sulfide polymers has now been discovered. The discovery that titanium dioxide could be added directly during the polymerization of arylene sulfide polymers to achieve consistent color was completely unexpected even though titanium dioxide is known in the art as a pigment and as an additive in arylene sulfide polymer compositions.